The present invention relates to a power transmission with a 5-stage planetary gear unit.
More particularly, it relates to a power transmission with a planetary gear unit with a first transmission shaft connectable with a drive through a reverse mechanism and a coupling, a second transmission shaft connected through hydrostatic adjusting mechanism with the drive, and third, fourth and fifth transmission shafts connected with at least one power take-off through a corresponding toothed gear transmission stage and an associated gear shift coupling.
Such a power transmission is disclosed for example in the German document DE-C1-43 23 358. In this transmission the hydrostatic adjusting mechanism is always coupled at the input side with the drive unit, and from it the planetary gear unit is controlled on the one hand which on the other hand is coupled through the reverse coupling with the drive unit. Thereby the adjusting mechanism runs idly, or in other words when no gear stage is introduced and the coupling is not actuated, always with the swinging-in adjusting unit. During starting first the reverse coupling is turned on and simultaneously the hydrostatic adjusting unit fully swings out, so that at the planetary gear unit a balance of both drive units is provided, or in other words a so-called regulated zero point is obtained, and a vehicle connected at the output side is stopped. During turning back of the adjusting unit the vehicle starts the drive in correspondence with the rotary speed difference of the planetary gear unit. This obtaining of the parallelity of the coupling-in step and swinging-out of the adjusting unit, or in other words holding of the regulated zero point, poses high requirements to the electronic control of the associated adjusting means. The angle acceleration steps which for the different adjusting means actuate with respect to the power pickup must be brought completely parallel since in the event of a timely different engagement of the reverse coupling when compared with the swinging step, a power pickup can be performed in a not desired direction which endangers the safety and is completely unacceptable, in particular for vehicles. The further disadvantage is that during reversing the adjusting unit in standstill must be adjusted to the opposite extreme position so that for reversing takes unacceptably long time.